The female vagina is naturally colonized by a variety of bacteria, yeast, and microorganisms. For example, a normal vagina generally contains more than about 104 lactobacilli per milliliter of vaginal fluid. Under normal conditions, the vagina flora provides a mildly acidic environment that helps guard against the invasion of pathogenic microbes. Unfortunately, this vaginal balance may be easily upset by a variety of external factors that ultimately lead to vaginal infection. Vaginal infection is a clinical syndrome and exists in three primary forms, i.e., bacterial vaginosis, candidal vaginitis (“yeast”), and trichomonas vaginitis (“trich”).
Bacterial vaginosis, for example, is a polymicrobial vaginal infection believed to be caused by an increase in the number of anaerobic organisms with a concomitant decrease in lactobacilli in the vagina. The decrease in the number of lactobacilli in the vagina has the dual effect of decreasing competition for nutrients and decreasing the amount of lactic acid present (i.e., increasing the pH). This allows for the multiplication of opportunistic pathogens in the vagina, whose growth is normally suppressed by the lactobacilli and the acidic pH of the vagina. The principal pathogen associated with bacterial vaginosis is believed to be Gardnerella vaginalis. Symptoms of bacterial vaginosis generally include an unpleasant smell, an elevated vaginal pH greater than about 5.0, a thin homogeneous discharge, and the presence of Gardnerella clue cells (i.e., vaginal epithelial cells coated with small Gram-variable rods). Current treatment regimens for bacterial infection of the vagina involve the use of various broad spectrum antibiotics, such as metronidazole. However, antibiotics are often undesirable because they may kill a broad range of the normal bacterial flora in the vagina, including the beneficial lactobacilli. This may cause secondary complications, because the lactobacilli keep various opportunistic pathogens in the vagina in check. The treatment may then necessitate a further treatment regimen, such as the ingestion of cultured dairy products to replace the lactobacilli in the body, as well as treatment by antifungal agents. Moreover, a rise in the level of anaerobes due to a lack of lactobacilli could further complicate the infection. Additionally, antibiotics, when used frequently within the vagina, may cause systemic toxicity through absorption from the vagina.
In addition, trichomonas vaginitis (or “trich”) is one of the most common vaginal infections and is considered a sexually transmitted disease. Symptoms of trichomonas vaginitis include vulvar itching and odorous vaginal discharge. Trichomonas vaginitis is caused by Trichomonas vaginalis, a single-celled protozoan parasite not normally found in the flora of the genitourinary tract. Trichomonas vaginalis is a flagellate protozoa that is pear-shaped and about the size of a white blood cell. These motile cells have four flagellae and a single nucleus. Like bacterial vaginosis, this pathology is generally treated with metronidazole.
Further, the yeast Candida albicans causes the disease known as candidiasis (or “thrush”), as well as vulvitis (or “vulval” infection). Candida albicans is present in most humans as a harmless commensal organism. Problems arise, however, when a person experiences a loss of normal bacterial flora. In severely immune compromised patients, for example, Candida albicans infection may spread throughout the body and cause systemic infections. Candidiasis is usually treated with fluconazole, but this may have serious side effects and is not recommended for use during pregnancy.
In view of the some of the problems discussed above, various alternative treatment regimens have been developed. For example, one regimen for treating vaginal infection includes the repeated application of intra-vaginal cream or gel over a period of several days to about a week. However, many conventional cream or gel compositions readily leak from the vagina, thereby causing an undesirable feel for the user. The leakage of the gel also causes the therapeutic agent to break contact with the vaginal tissue after only a short period of time, thus reducing its potential effectiveness against vaginal infection. Another problem with some gels is that they prematurely gel. For instance, the formation of certain gels is induced by a change in temperature (i.e. thermogels). Unfortunately, during storage or shipping, these gels may be placed in a hot environment that causes a gel to prematurely form. After an extended period of time, the strength of such gels deteriorates to an extent that significant leakage will likely occur during use.
As such, a need currently exists for an improved vaginal treatment composition.